This invention relates generally to the closure and filling of soft tissue sites with self-expandable, bioresorbable, biopolymeric implants, particularly to the closure of percutaneous puncture sites. The present invention is particularly directed to the delivery of such implants with delivery devices which penetrate the soft tissue sites to a defined depth for hemostasis and wound closure. Methods of preparing the implants are also disclosed.
It has been routine practice to insert a cannula through a puncture site into a blood vessel for treatment of that vessel, a procedure known in the art as percutaneous transluminal angioplasty. In this procedure, an introducer sheath is inserted into an artery through the puncture site such that a balloon or other type of catheter can then be inserted into the vessel to carry out the procedure within a vessel. One of the complications of this and related procedures is hemorrhaging at the percutaneous puncture site after removal of the catheter and the introducer sheath. In order to stop the bleeding, pressure is applied at the puncture site until hemostasis occurs. Since angioplasty and related procedures often require the use of an anticoagulant, the pressure approach is not always effective and may require a long period of pressurization and occasionally surgical treatment. In some cases, prolonged hospitalization is required.
The invention relates to the precise delivery of an implant member at an incision extending through tissue and at a lumen wall within a living body to stop the bleeding in post angioplasty and related procedures. The implant member is formed of a material adapted to close the incision (e.g., a self expandable, resorbable, hemostatic and wound closure implant).
In a general aspect of the invention, an implant delivery device includes a detector disposed in fixed relation to a cannula inserted within the incision to detect the presence of body fluid flowing in the lumen, thereby locating the implant member at the wall of the lumen. The implant member further includes a retaining member slidably positioned within the cannula to maintain the implant member at the wall of the lumen when the cannula is withdrawn from the incision.
Preferred embodiments may include one or more of the following features.
The detector includes a tube (e.g., a capillary tube) having a hole disposed near a distal end of the tube to receive fluid from the lumen. The hole conveys the fluid into the tube. The hole is iteratively moved into and out of the lumen, to locate the implant member at the wall of the lumen. In one embodiment, the tube has a sealed distal end and the hole is positioned at the distal end and on the side of the tube to convey fluid through the tube and to a proximal end of the tube disposed external to the living body near a proximal end of the cannula. The proximal end of the tube has an opening through which the conveyed fluid exits. For example, the tube may be made narrow (e.g., a capillary tube). In another embodiment, a pressure monitor is connected to an opening at the proximal end of the tube. In this case, the tube may have a wider dimension than the embodiment in which fluid flows to the proximal end of the tube so that the difference in the pressure of air within the tube can be detected. Moreover, the distal end of the tube need not be sealed but may include the hole at the distal end to detect the systolic pressure of blood flowing in the blood vessel.
In another embodiment, the detector includes a pressure sensor positioned at a distal portion of the cannula. The sensor is moved into and out of the lumen to detect the difference between a pressure within and outside the lumen, thereby locating the implant member at the wall of the lumen.
The retaining member may include an elongated member having a flat plate formed at a distal end of the elongated member and a thumb rest attached at a proximal end of the elongated member.
In another aspect of the invention, the implant delivery device described above is positioned to close an incision at the lumen wall using the following steps. The implant member is placed within the distal portion of the cannula. The cannula is then positioned within the incision to detect the presence of body fluid flowing in the lumen, thereby locating the implant member at the wall of the lumen. The implant member is released from the cannula and maintained at the wall of the lumen by withdrawing the cannula from the incision.
In one embodiment, a retaining member is slidably positioned within the cannula with a distal end of the retaining member contacting a proximal end of the implant member. In use, pressure is applied to the proximal end of the retaining member while simultaneously withdrawing the cannula.
In still another aspect of the invention, a method of positioning an implant member to close an incision extending through tissue and the wall of a lumen within a living body includes the following steps. The implant member is placed within a distal portion of a cannula. A detector is positioned in fixed relation to the cannula. The cannula and the detector are positioned within the incision. The cannula and detector are moved to detect the presence of body fluid flowing in the lumen, thereby locating the implant member at the wall of the lumen. The implant member is then maintained at the wall of the lumen while simultaneously removing the cannula and the detector from the incision.
The implant member is a resorbable, self-expandable tissue and wound closure implant and is generally formed as a dry, compressed porous matrix comprised of biological fibers. As used herein xe2x80x9cbiological fibersxe2x80x9d include natural fibers derived from collagen, elastin, fibrin and polysaccharides as well as bio-synthetic analogs of the natural fibers derived by bioengineering methods such as recombinant DNA methods. In a preferred form of the invention, the matrix is comprised of collagen based fibers of animal or humans.
In particular, the compressed porous matrix of the present invention comprises a matrix having a density from about 0.05 g/cm3 to about 1.0 g/cm3 (preferably, from about 0.1 g/cm3 to about 0.3 g/cm3), and pores of a dimension from about 0.5 xcexcm to about 50 xcexcm (preferably, from about 1 xcexcm to about 10 xcexcm) in a dry state. The pore size is defined as the gap distance of an elongated pore and is measured by the method described in the working example given below or any analogous method. This compressed matrix self expands radially when in contact with an aqueous medium resulting in pores with a dimension of from about 100 xcexcm to about 1,000 xcexcm in its fully expanded configuration, and a corresponding expansion of volume of from about 2 cm3/cm3 to about 100 cm3/cm3 (preferably, from about 10 cm3/cm3 to about 30 cm3/cm3); and a reduction of density to about 0.01 g/cm3 to 0.10 g/cm3 (preferably, about 0.02 g/cm3 to about 0.06 g/cm3). Preferably, the implant member has a diameter in a range between 1 mm and 6 mm in its compressed state and 5 mm to 50 mm in its fully expanded state, and has a height in a range between 2 mm to 100 mm, which is about the same in either state (e.g., the height in the expanded state is only about 10% or 20% greater than that in the compressed state). The implant member has a relaxation recovery time which ranges from 1 second to 60 seconds (preferably, from 1 second to 20 seconds) can be measured by the method described in the working example given below or any analogous method.
The method for fabricating the resorbable, self-expandable tissue closure implant, in its broadest embodiment, comprises:
a) forming an aqueous dispersion containing biological fibers;
b) pouring the aqueous dispersion into molds;
c) freeze-drying the aqueous dispersion;
d) crosslinking the freeze-dried matrix by treatment with crosslinking agent;
e) spraying the crosslinked matrix with water mist; and then
f) compressing the water mist treated matrix.
The resorbable, self-expandable, soft tissue wound closure implant of the present invention is constructed such that the matrix is highly compressed to provide maximal volume expansion capacity and surface area for fluid absorption, platelet adhesion and hemostasis while maintaining minimal volume for insertion. The highly porous matrix upon expansion also provides maximal surface area for cell infiltration and adhesion for wound healing.
Other features and advantages of this invention will be apparent from the following drawings, detailed description, and claims.